1. Field of the Invention
The present invention relates generally to urban inductrack maglev systems utilizing Halbach arrays and, more particularly, to an improved close-packed shorted circuits track elements for use therewith.
2. Description of the Related Art
Halbach arrays utilize cross-magnetized magnet bars in an array is to enhance the periodic magnetic field at the front face of the array, while canceling it at back face of the array. Not only is the field enhanced, but analysis shows that in a long array the horizontal and vertical components are nearly purely sinusoidal in their spatial variation, with negligible higher spatial harmonics.
Such a system is currently under construction as part of the Department of Transportation""s Urban Magnetic Levitation Transit Technology Development Program being administered under the Federal Transit Administration. Such a system being built is a prototype for testing of lower-speed applications of magnetic levitation, such as for urban train systems, and is attempting to employ systems that are simple in construction and operation and that have low drag at urban speeds.
The first-proposed Inductrack disclosed in U.S. Pat. No. 5,722,326, titled xe2x80x9cMagnetic Levitation System For Moving Objectsxe2x80x9d, referred to herein as Inductrack I, employs special arrays of permanent magnets (xe2x80x9cHalbach arraysxe2x80x9d), on the moving train car to produce the levitating magnetic fields. These fields interact with a close-packed ladder-like array of shorted circuits in the xe2x80x9ctrackxe2x80x9d to levitate the train car. In this first form of the Inductrack, single arrays moving above the track produced the levitation. In the Inductrack maglev system Halbach arrays are used, located below the train car. When in motion the magnetic field of these arrays then induces currents in a special xe2x80x9ctrackxe2x80x9d made up of close-packed shorted circuits. The close-packed shorted circuits consist of a series of conductive rungs electrically connected at the ends. The rungs consist of stainless steel tubing swaged over Litz cables. Litz cables are actually stranded film insulated conductors, or stranded magnet wires, which are cabled into a geometric pattern permitting each wire to occupy every possible position in the entire length of the cable at some point. The reason for this arrangement is to reduce losses caused by the tendency of currents to flow only on the outside surface of wires at high frequencies. The Litz cable carries the induced current from a changing magnetic field, which in turn proives the magnetic lift. The stainless steel tubing around the Litz cable carries the vehicle weight due to the magnetic levitation. The Litz track rungs are soldered into a copyer shorting bar that allows the current to pass between the rungs.
The present invention deals directly with an improvement in design and manufacture of the making up the Litz rungs and shorting bars of the close-packed shorted circuits.
A search of the prior art did not disclose any patents that read directly on the claims of the instant invention; however, the following references were considered related:
Consequently, a need currently exists for providing improvements in design, construction and costs for any component used in an urban inductrack maglev systems utilizing Halbach arrays.
It is therefore an object of the present invention to provide an improved track Litz rungs and shorting bar design for urban maglev inductrack.
It is a feature of the present invention to provide an improved process for making Litz rungs for use with an Urban Maglev Inductrack.
Briefly described according to the preferred embodiment of the present invention, improved Litz track rungs for urban Maglev Inductrack use is disclosed, as well as an improved method for making the same. Rather than using a stainless steel plate and forming the square tube around the required copper Litz cable, a standard square stainless steel tube is formed by itself using otherwise conventional means. Each tube is cut to length and otherwise worked to the required specification, particularly, relief holes can be drilled that allow for release of gases that are generated when the rails are soldered to form the electrical connection with the shorting bars. After being worked, the tubes are annealed by heat treating at 1900 degrees, thereby removing the strain and stress hardening generated during the process of forming the square shaped stainless steel tube. An additional unrealized side effect of the annealing process is the removal of the slight magnetism generated into the stainless steel tube by the metal working process. Subsequently, a stress relieved, demagnetized square tube is thereby provided for further manufacture by installation of a square packed Litz cable within the square tube and compression of the rail using a punch press or brake to compact and compress the rail, thereby minimizing electrical resistance and increasing overall electrical conductivity of the rail.
An advantage of the present invention is that improved close-packed shorted circuits track elements are created.
Another advantage of the present invention is that improved close-packed shorted circuit track elements are created having less stress hardening generated during their formation.
Another advantage of the present invention is that Maglev inductrack rungs are formed having a lower interfering permanent magnetic field within the stainless steel outer shell.
Another advantage of the present invention is that Maglev inductrack rungs are formed in the absences of flood cooling, thereby reducing problems associated with increased levels of internal moisture.
Further, a preferred embodiment of the present invention can hereafter be formed using standardized, commodity materials rather than utilizing a custom fabrication method, thereby greatly reducing the cost of a component used in great quantity in building an system utilizing Halbach arrays.